Jump to content

  • Log In with Google      Sign In   
  • Create Account


#ActualJTippetts

Posted 16 December 2012 - 06:07 PM

You seem to have your terminology a little bit confused.

Orthographic projections are any class of projection where the projection lines (the lines along which points are projected onto the 2D view plane) are all orthogonal (ie, perpendicular) to the view plane. That is, there is no shrinking or perspective as the object gets further away.

Video games commonly use a subset of orthographic projections that are loosely called isometric projections, but are more accurately called axonometric projections.

The most common axonometric projection used in games is one where the camera is oriented at an angle 30 degrees above the horizon, 45 degrees around the vertical axis. This results in a dimetric projection. This projection is nice because it results in the classic 2:1 tile ratio (ie, tiles on the ground are twice as wide as they are tall) making it fit neatly in the powers-of-2 requirement for textures on older hardware. The first 2 Diablo games used this projection (though D2 provided an optional skewing to fake perspective) Many F2P MMOs and many RTS games also use this projection. In this projection, the X and Y axes (lying parallel to the ground plane) are equally fore-shortened, while the vertical (Z) axis is foreshortened a different amount.


An angle of ~35 degrees above the horizon results in a true isometric projection in which all 3 axes are equally foreshortened. This is used somewhat less frequently, as the tile sizes are weird.

Some older RPGs used a trimetric projection, where all 3 axes were unequally foreshortened, usually by using some value other than 45 degrees for the rotation around the vertical axis. These, also, are somewhat less common, again for the weird tile sizes.

Again, it might be helpful to give us a screenshot of what you want, for those of us who don't let Java onto our machines.

#1JTippetts

Posted 16 December 2012 - 06:06 PM

You seem to have your terminology a little bit confused.

Orthographic projections are any class of projection where the projection lines (the lines along which points are projected onto the 2D view plane) are all orthogonal (ie, perpendicular) to the view plane. That is, there is no shrinking or perspective as the object gets further away.

Video games commonly use a subset of orthographic projections that are loosely called isometric projections, but are more accurately called axonometric projections.

The most common axonometric projection used in games is one where the camera is oriented at an angle 30 degrees above the horizon, 45 degrees around the vertical axis. This results in a dimetric projection. This projection is nice because it results in the classic 2:1 tile ratio (ie, tiles on the ground are twice as wide as they are tall) making it fit neatly in the powers-of-2 requirement for textures on older hardware. The first 2 Diablo games used this projection (though D2 provided an optional skewing to fake perspective) Many F2P MMOs and many RTS games also use this projection. In this projection, the X and Y axes (lying parallel to the ground plane) are equally fore-shortened, while the vertical (Z) axis is foreshortened a different amount.


An angle of ~35 degrees above the horizon results in a true isometric projection in which all 3 axes are equally foreshortened. This is used somewhat less frequently, as the tile sizes are weird.

Some older RPGs used a trimetric projection, where all 3 axes were unequally foreshortened, usually by using some value other than 45 degrees for the rotation around the vertical axis. These, also, are somewhat less common, again for the weird tile sizes.

Again, it might be helpful to give us a screenshot of what you want, for those of us who don't let Java onto our machines.

PARTNERS